Infection control and cross infection present a major problem for hospitals today, leading to considerable expense and inconvenience. Bacterial strains have developed which are increasingly more resistant to treatment by antibiotics. Therefore, once an infection is established in a hospital, it is often difficult to eradicate and can spread quite rapidly. A problem known as “strikethrough”, where a contaminated fluid penetrates to an interior of a infection control bedding product such as a pillow, duvet, mattress, or cushion, is well known. If “strikethrough” occurs, then there is a considerable risk of cross infection associated with any of these infection control bedding products since they are likely to be used subsequently by many different patients. Indeed, this problem arises in any situation where there is a regular change in persons using pillows, duvets and the like, such as, for example, in hotels and guesthouses. Furthermore, in the home, many people with allergies and breathing disorders have problems with fungal infection and dust mites.
There are numerous commercially available materials typically used for waterproof covers on mattresses, typically comprising a knitted or woven nylon fabric, with a thermoplastic coating, typically polyurethane, applied. The knitted or woven fabric provides mechanical strength, while the thermoplastic (polyurethane) coating provides waterproofing.
Some such fabrics are termed “vapour permeable” because tiny pores exist at sub-micron level in the coating, that nominally allow transport of water vapour molecules. However, these fabrics do not allow transfer of air at sufficient rates to ventilate a pillow.
U.S. Pat. No. 4,637,377 discloses a surgical pillow for supporting the heart or other body organs of a patient during surgical procedures. The surgical pillow disclosed in U.S. Pat. No. 4,637,377 has a foam filled casing with a vent in the casing to permit release of entrapped air within the casing upon compression of the pillow during use.
U.S. Pat. No. 5,038,431 discloses a pillow for dispensing medication. The pillow has an outer sheet forming a pocket for reception of filling material. The pocket has a vent opening and the filling material is impregnated with a medicament. When the vent is open, a person is exposed to medicament vapour which escapes through the vent opening.
These prior art pillows do not address the problem of “strikethrough”.
U.S. Pat. No. 4,445,241 discloses an air tight and fluid tight cover for padded bodies, mattresses and the like. The cover has a top, a bottom and a plurality of side parts. At least one opening provides ventilation between the interior of the cover and the ambient atmosphere. At least two of the side parts are formed by at least an interior, middle and exterior layer of material. Air passage openings offset with respect to each other are provided in the interior and middle layers of material. At least one filter is disposed between the middle and outer layer of material. A plurality of connecting seams extend partially transversely across the width of the side part from diametrically opposite points of the upper and lower longitudinal edges of the side parts toward a longitudinal center line bisecting the side part. The connecting seams define a plurality of pockets in which the filters are disposed. The connecting seams also define air passages between the individual layers of material for trapping coarse granular particles therein.
U.S. Pat. No. 4,445,241 discloses a moisture and air-tight cover for a pillow in which welded seams are provided to constitute pockets for reception of filters for particles and bacteria. This is a complex product which is difficult and expensive to produce. The seams define a serpentine air passage between the interior and exterior of the pillow and each air stream contains at least two filters. However, these filters are not, and cannot be, physically connected to one another by welding or otherwise, as in the present invention, and in fact at least one filter at the outer opening of the air passage can be removed through slit-shaped openings 28 (see column 4, lines 13 to 15). The serpentine passage actually provides a breeding ground for bacteria thus defeating the purpose.
A further distinction and advantage of the present invention as compared to U.S. Pat. No. 4,445,241 is that the filter cannot be removed from the pillow deliberately or inadvertently, thereby possibly compromising the filtration, as is possible with the design of U.S. Pat. No. 4,445,241.
A major problem to overcome when developing a sealed pillow is to ensure adequate ventilation of the pillow core. A pillow may be made airtight by using an occlusive medium for the cover, and welding the seams. However, the lack of ventilation in such a pillow creates problems in use, such as the following problems:                1) When the head rests on the pillow, the pillow does not deflate. This is uncomfortable, and creates an unstable surface for the head to rest on.        2) Impact to the pillow, either accidentally or when the head first makes contact, creates a great deal of stress on the seams, which may burst as a result.        3) Gradual ingress of water vapour particles by diffusion creates condensation within the pillow, leading to accelerated degradation of the materials within.        
Furthermore, many attempts have been made to provide pillows, cushions or mattresses that have a barrier for contaminant particles or liquid, but none has been entirely successful. The best effort to date and currently in use in the healthcare sector, is the pillow disclosed in the Applicants' patent specification no. EP 1 222 886. Nevertheless, the infection control bedding product of the present invention provides significant advantages over the pillow disclosed in EP 1 222 886.
European Patent Specification No. EP 1 222 886 discloses a pillow comprising a sealed outer liquid impermeable cover, filling material retained within the outer cover, a vent in the cover communicating between an interior and an exterior of the cover and a bacteriological air filter means mounted across the vent to provide for filtering of air passing through the vent, wherein the filter comprises an outer layer of liquid-resistant material with a number of superimposed inner filter material layers attached to the outer layer, and wherein the material layers are welded together and to the cover across the vent. Provision of a bacteriological filter prevents the ingress of bacteria to an interior of the cover.
The outer layer of the filter of the pillow disclosed in EP 1 222 886 does not provide adequate liquid resistance. Even if a filter medium constructed using the same materials as the outer layer of the EP 1 222 886 filter could be made to be fully liquid resistant, such a filter medium would not provide adequate ventilation for the product to breathe, resulting in ballooning of the pillow in use. This would provide an uncomfortable surface for a user to rest on, and could burst from internal pressure when in use. In addition, the method of welding each of the five layers of the filter of EP 1 222 886 is time consuming and inhibits the viability of the product from a mass production and commercial point of view.
For example, EP 1 222 886 only teaches a liquid resistant as opposed to a liquid proof outer layer to the filter. The textile disclosed in EP 1 222 886 is a nylon material which will admit liquid at relatively low levels of pressure (i.e. relative to the membrane of the present invention). If the textile disclosed in EP 1 222 886 was made liquid proof, it would require that the pore size would be reduced to such an extent that such pore size would prevent the pillow from “breathing” or deforming, or inhaling/exhaling to the required level.
The present invention addresses and solves these technical problems. As will be further described in detail hereinbelow, the filter membrane included in the present invention is more like a strengthened skin that breathes through osmosis. This is in contrast to the filter of EP 1 222 886 which must be more coarse in order to form part of the product and is only liquid resistant rather than liquid proof. The pillow of EP 1 222 886 has a woven synthetic outer textile backed by non-woven polyester layers. The membrane of the present invention is fundamentally different from the medium disclosed in EP 1 222 886.
The filter membrane in accordance with the present invention overcomes a number of technical problems. The filter membrane included in the present invention, being like a thin skin, must be strengthened so that the infection control product of the present invention would be fit for use in the environment in which it would be used and so that it could withstand the challenges that are likely to be present in use. This needed to be achieved without compromising key properties of the filter medium and the pillow including filtration of contaminants and “breathability” of the pillow.
EP 1 222 886 discloses the welding together of five or six layers of material. If, as is taught in EP 1 222 886, each layer is welded to the other and then to the liquid resistant outer fabric and then the whole medium is welded across the aperture in the pillow, then the process becomes non-viable from a manufacturing and mass production point of view. If they are all welded together in one action, then the seal integrity and consequently, the pillow is compromised as the strength and integrity of the seal between each individual layer is compromised. Further, the drawings and description of EP 1 222 886 illustrate that the filter medium should run diagonally and be welded at one end into the top seam of the pillow and at the other end into the side seam of the pillow. This means that a further thick 2 thick layer of PU-coated fabric need to be welded through, in addition to the 5/6 layers of the medium, thereby giving rise to further manufacturing challenges and quality/integrity issues. In other words, EP 1 222 886 does not teach a product that when mass-produced can provide the benefits of the present invention.
A further problem that emerged with the pillow disclosed in EP 1 222 886 was that the filter medium itself as well as the seal between the filter medium and the pillow cover could burst or tear if pressure equivalent to a patient leaning on their elbow, was applied directly on the filter medium itself. Therefore, a further problem overcome by the present invention is the provision of a new and vastly improved filter medium that could withstand pressure of this nature whilst providing efficient bacteriological properties.
The filter medium disclosed in EP 1 222 886 is described as efficient to block the passage of particles having a size of 0.6 microns or greater whereas the present invention including a new medical membrane design which has been proven to be efficient to block the passage of particles having a size of 0.2 microns or greater. Therefore the present invention addresses a greater number and wider category of possible contaminants.
Accordingly, the present invention relates to an improved infection control bedding product, e.g. a pillow, having technical improvements in particular, superior liquid resistance over the pillow disclosed in EP 1 222 886.